The invention relates to a broad-drawing apparatus for moving webs of material, particularly webs of paper, whose roll consists of a plurality of individual sections mounted on shaft sections, a two-part thrust bearing determining the degree of curvature being provided for the adjacent shaft sections of every two adjacent roll sections.
A prior-art broad-drawing apparatus of this type (U.S. Pat. No. 3,786,975) makes it possible to prevent wrinkling of the web of paper, foil, cloth or the like by setting the roll by means of individual thrust bearings for a particular curvature at which slack web edges or individual sagging areas in specific zones over the width of the web are eliminated. The two-part bearing further permits individual roll sections to be inserted or removed without the whole broad-drawing roll having to be removed. For this purpose, adjacent shaft sections are provided with facing clutch portions of rectangular cross section which are surrounded by matching recesses in the corresponding thrust-bearing parts. In the assembled condition the thrust-bearing parts are in interlocking engagement with the clutch portions.
It has been found that with this type of engagement the tight fit between the thrust-bearing part and the clutch becomes loose in the course of operation since in the vertical positioning of the thrust bearings and in the removal and insertion of the individual roll sections the clutch portions execute a tilting or angular motion in the recesses of the thrust-bearing parts, and this leads to deformation of the material of construction. The result is unsteady motion and vibration in operation.